Hydraulic log-barker having kerfcutting and bark-removing jets



Sept. 23, 1952 R. E. BURTON HYDRAULIC LOG-BAKKER HAVING KERF-CUTTING AND BARK-REMOVING JETS 3 Sheets-Sheet L Filed 0G19. 17, 1950 l" INVENToR.

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Sept.v23, 1952 R. ET BURTON v 2,611,401

. HYDRAULIC LOG-BARKER HAVING KERF-CUTTING AND BARK-REMOVING JETS Filed om.` 17, 195o 3 Sheets-Sinaai 2 Patented Sept. 23, 1952 HYDRAULIoLoG-BARKER HAVING KERF-V CUTTING AND BARK-REMOVING JETS Robert .Edward Burton, Willits, Calif. 'Application october 17, 195o, serial N0.`.19o,549

2 Claims. 1

This invention relates to a method for debarking logs by hydraulic means, and to apparatus for carrying out the same.

In commercial lumbering operations the debarking of logs is accomplished in one of three ways; either by hand, by mechanical means or hydraulically. At vthe present time a considerable portion of all debarking is accomplished by hand labor. While the hand operation has the advantage of producing a good product and 'requir-Y ing almost no capital investment, it has the disadvantage of being expensive and tedious. Me-

fchanical debarking is accomplished either by beating the bark to loosen it from the wood portion, or by cutting the bark off such as byshaving it in a large lathe. Both of these methods have the disadvantage of requiring substantially large capital investments in the machinery involved and of either producing a poor product or of being wasteful of the wood.A

Hydraulic debarking methods making use of a jet of water, have in the past included one of three methods involving either eroding of the bark, beating of the bark, or blasting and disinrate and uses large volumes of water. Therefore this process has a low efciency and economy and I is generally'unsuitable. The mechanical beating operation employing a plurality of whirling chains has been simulated'in the hydraulic field by the employmentv of large volumesof water in the 600 to 1400 pounds per square inch range. In this method the force of the water is used to beat and loosen the bark from the wood portion of the log. This method has the disadvantage of requiring relatively large volumes of Water -at a high power 'cost as well' as the inherent disadvantage of all beating processes whether mechanical or hydraulic' inthat when the bark is spongy, fibrous or `soft its corresponding shockabsorbing characteristic results in further lowering of the' efficiency.V

The disintegration or blasting method also operatesin'the 600 to 1000 pounds per square inch range and operates upon the principle of concentrating upon one small area of the bark at a time, the object being to direct a considerable volume of water in a localized area to cause disintegration and blasting away of the bark in that local area. This method also has the 'disadvantage of requiring a considerably'large volume'of water and operates with la relatively high" power consumption. In general, therefore, all hydraulic methods of debarking which have been known before my invention have had the inherent disadvantage' of very low eiiciency and havev been wasteful of both water and power.

It is an object of my invention to provide-a method and apparatus for debarking logs which will overcome the faults of prior hydraulic debarkng as set forth above.

Another object of my invention is to provide a method and apparatus for debarking logs which will require a relatively low volume o f water in its operation.

Another object of my invention is tor provide a method and apparatus for debarking logs whichis simple both to install and operate and which will require a substantially lower capital expenditure' than that required for those methods employing any of the methods outlined above.

A further object of my invention is to provide a method and apparatus for debarking logs which is rapid, efficient and economical in operation.

Additional obj ects and features of my invention will appear from the following description in which the preferred embodiments have been set forth in detail in conjunction with the accompanying drawings.

Referring tothe drawings:

Figure 1 is an end elevational view illustrat ing one form of apparatus for carrying outmy invention.

Figure 2 is a plan view o-f the apparatus shown in Figure 1.

Figure`3 is a fragmentary elevation of the barkremoving jets, as seen from the leftend of Figure l.

Figure 4 is a fragmentary elevation similar Vto Figure 3, but shows apparatus employing another embodiment of my invention.

Figure 5 is a fragmentary end view showing vthe embodiment of my invention as shown in Figure 4.

In general my invention utilizes the combined effect of at least two hydraulic jets, one whichl is a leading jet which cuts through the bark, followed by a peeling jet or`jets which serve to peel the eut bark from the wood portion of the log. Both the cutting action and the peeling action are accomplished'through the use of relatively low volumes of water in comparison lto previous hydraulic methods.

A suitable apparatus Afor carrying 'outI the method of my invention is shown in Figures l and 2. While any suitable means may be used for holding and rotating the log I during debarking operations, I have shown in Figures 1 and 2 a series of rollers i I mounted in pairs connected on each side by a pair of common shafts I2. Chain or belt drives I3 connect each of the shafts together and to the common drive motor I4 through the sprockets or pulleys I5. .I haveshown Veach roller I I provided with an outer tooth or serrated peripheral ring I6 to prevent slippage between the rollers and the log. Pillow blocks I'I serve-to journal the rollers and their shafting to the foundation bed I8. Y

In order to facilitate the handling of logs so that they may be easily fed to the-machine, I have provided the ramp or skid I9. For removing the log after its debarking operation has been completed suitable means such as the vcrescent-- shaped lifting arms 20, rotatable about their .pivot points bythe hydraulic piston-means 2 I, may be employed.

vAsshown in the apparatus of Figures 1 and 2,

a pairof high velocity hydraulic nozzles 22 and .23-are mounted adjacent the-outer surface of the .log and upon vthe Isupport arm 24.

-Nozzle 22 directs a cutting jet which serves to cut through the bark to the wood portion of the log. 'Nozzle 23 'directs a barkpeeling jet-which serves -to 'revmove `the barkV from the wood portion of the-log vsubsequent tothe cutting-operation. Asshown,

nozzle 22 is positioned -upon thesupportarm- 24 vso that the jet which it-produces-.will be directed through the bark to the-wood portion in-a direcvtion along a radius of the log. The nozzle 22 is f connected to a flexible hose 26 of the type capable of withstanding substantially high lluid pressures, as for exaznple-watc-:raty a pressure of from 3000 -to -5.060- pounds per: square inch. Hose Y26 is in turn connected to hydraulic pumpmeans capable-of deliveringavolumefof Watan-for example, from 3 to 5,-gallons per minute-at vpressures up iso-,5000 pounds-per square inchA IAS-shown, nozzle 23 is mounted upon the supportarm 24. so thatv the-jet-Which it produces is directed into the groove or kerf-.made :by the cutting-jet. Nozzle-23I is adapted toproduce a 4relatively high velocity compact jet when con- .nected by flexible hose- 21 to -a suitable pump capable of delivering for exampleea-volume of from 10 to 22 gallons per minute -atia pressure of 1500-to 2000 pounds'per-square inch.

Supporti arm 24is provided Vvwith a counterweight 29 and guard rail 3!)A and is pivotally and movably mounted by means which will: be presently explained. By such mounting thesupport `arm- 24 vis movable the entire length ofthe log as .well as pivoted for vertical movement -to permit the loading and unloading of logs from the .apparatus as well as for adjustmentto size and irregularities of the le gs. -Nozzles 22 and 23 are maintained at a co nstantdistance from the surface of the log -by suitable means such as a pair .of small wheels 28. Wheels-28 are so mounted that their support axles may be turned for posi- 1 tioning about an extended radius ofthe log. By

lturningand positioning each of thewheelsz28 to 4 zles. I can provide suitable anchoring facilities by mounting the guide rail 3| parallel to the log upon a series of support columns 32. Carriage means 33 provides pivotal and movable support along rail 3| for the support arm 24. Carriage 33 can include two pairs of rollers 34 for engaging either side of the web of the rail 3I. To support the carriage means I can provide a pair of rollers 3Std roll upon .the head of the.` rail. i Rollers 35 serve as-a fulcrum for'the arm 24 and permit the arm and attached nozzles to be raised and lowered from the horizontal to provide for ir- .regularities-in the diameter of the log, logs of -various"diarneters, and for loading and unloading. Bumper stop 31 can be provided extending parallel to the length of the apparatus and positioned beneath counterweight 29 to prevent undue movement of the support arm 24 about its fulcrum.

Having thus described one form of the appat ratus sui-tablefor use-with 'myY invention: Iishall nowdescribe. the-mode of; operation off' such-'apparatus and method of my-.in-vention. 4'llo-permit the loading oa'log, support-arm may be moved-teorie end of thetrackfas -for example-the extremeA lefthand portion-of Figure2,-or itmay ...belifted upwardly as- -byhaving -the operator -walkto thewright end -4 asviewedin Figure 1.

,Once-the log-has been rolled from ,theskid upon the-rollers the support armf-mayfbe'moved'to `theV beginning position,-which,--as viewed in Fig- .ure 2, `isv the extreme right-hand portion ,aas

shown in that illustration. `Rotation, of--the,-log is begun lay-starting :motor-1 I4. Due tothe-.angle vat which .the -axles of rollers` 2.8.:arezsetnto .the plane ofthe longitudinal -aX-is :offtne log,r -rotation ofthe -log- `will impart ytraversing.movement of the. support arm along-theilongitudinal length of the log-to its oppositerend.

Hydraulic pumps 'arestartedzftoa, supplywater at suitable' high pressures-.toeachoi the .-nozzles v22 and'23. The cutting J'et'which nozzle- 22;.pro- ,duces is `directed .-toimpinge radially :upon-the surface ofi-the; log and the :pressuresupplied to ythe nozzle` may. be-v regulatedto .control-the cutend-of the'log to the-other.

Following in thekerf- "made bythecuttingjet the peeling -jetproduced-by` nozzle' 23is`directed to break-awayand remove thecutbark from --the wood -portionof the log. Since the cutting-jetfhas formed --a-groc-ve through thei barkr to .the wood portion, the .peeling 'jet-working in cooperation therewith is 'directed to4 that -region'of' therlog lying-between the-wood. portion land thebark.

.This region vis known as the-cambial region'l and is composed -of' those f tree Vcells.` normally, -the .process of' adding tothe1growtl1-of the' wood:por

tion. I- have foundthat they peeling jetlshould be of a lcs-ser velocity and pressure than the-cut ting jet but` ofgreater volume to Yexert-more -force against the -bark in order tof-loosen` and iliftf the strips of cut -bark from the woodyportions ofy theV log. This pressure maybe of the order of from 1500.to.2000 s.-.i..atarate offrom Y10 Iso-'22 ..G. P. M.

I; have schematically; illustrated. `the :combined actiongof vthetwo jets in vFigure 3 of the drawings. As shown, the cutting jet first cuts through the bark 4| to the cambial region 42 but not into the wood portion 43 and produces the groove or kerf44. The peeling jet is directed to impinge substantially at the base of this kerf, in order that its force may be directed beneath thebark through the cambium region 42 to peel and remove the bark from the wood portion 43. As shown, the peeling jet is preferably positioned at an'angle of from 30 to 45 vto the plane of the wood portion surface of the log to properly impinge upon the cambial region and to breakv through that section of the log which forms a bond between the bark and Ithe. wood portion. The action of the peeling jet is such that it not only removes the bark from thewood portion but serves to carry the removed bark sections away from the log and the working area of the apparatus.

Once peeling of the log has been completed the supporting arm 24 is moved out of the way to permit removal of the log from the apparatus. Removal of the debarked log may be effected by rotation of the crescent shaped arms 20 about their pivot points 25 through the action of the hydraulic pistons 2l, thereby serving to lift and remove the log l from the rollers and to dump it into the receiving chute 38.

Apparatus for carrying out the method of my invention may be varied depending upon the characteristics of the wood encountered. For example, if the bark is so thick that it is impossible for the peeling jet to impinge upon the cambium layer at an angle to that area sufficient to effect peeling, as for example in the case where the angle of incidence of the peeling jet is of the order of from 60 to 90, it may then be desirable to use the modification I have shown in Figures 4 and 5. As shown in Figures 4 and 5, a peeling jet 23' is positioned to strike the log in the interval between the cuts made by the cutting jet. The peeling jet in this modification is directed to strike tangentially to the cambial region and at right angles to the longitudinal axis of the log. As shown, the peeling jet 23 does not impinge upon the log in the groove formed by the cutting jet, but is spaced from the cutting jet in a direction along the longitudinal axis of the log opposite to the direction of movement of the two jets along the length of the log. This method has been found quite effective in removing relatively thick bark from the wood portions of logs when using for example pressures of from 3000 to 5000 pounds per square inch at a now rate of from 3 to 5 gallons per minute for the cutting jet and pressures of from 1800 to 2500 pounds per square inch at a rate of now of from 9 to 22 gallons per minute for the peeling jet. In certain instances, by an obvious modification of the apparatus described, I have found it desirable in order to eiect more eilicient debarking to use a plurality of peeling jets positioned in a direction longitudinally of the axis of the log and preceded by the cutting jet.

Specific examples using apparatus similar to that described in Figures l to 3 inclusive for carrying out the method of my invention are as follows:

(a) Water was supplied to the cutting jet at a pressure of 4000 pounds per square inch at a volume of 3 gallons per minute, a cutting nozzle having an inside diameter of of an inch with its delivery end carried by the supporting arm at a distance of about 3 inches from the surface of the. log. Water ata pressure of '1800 poundsV per square inch at the rate of 9 Agallons per minute was supplied to a peeling nozzle which also had an orice diameter of 12' of an inch. The cutting jet wasdirected at an angle of yto the upper surface of the log and the peeling jet was directed at about a 45 angle to that surface vand impinged in' the cut made v.by the cutting jet. lA log of what is known as second growthv California redwood (Sequoia Semperivirens) vhaving a length of 5 feet anda 'diameter inside the bark of 7 inches was completely peeled in .'74 seconds. The peeling took place with the speed of rotation of the log at a rate of approximately 12 R. P fM. and with a speed of advance of the cutting and peeling jets sufficient to provide an interval of 4 inches between the lspiral cuts.,

(b) A log of Douglas iir having a diameter inside the bark of. 9 inches and a length of `5 feet Was peeled in 58 seconds under the same conditions of pressure, rate of flow, andijet'lpositioning as in Example a. The log was rotated at a speed of approximately 10 R. P. M. with an advance of the jet suiiicient to provide an interval of 3 to 6 inches between spiral cuts.

From the above examples it is apparentv that the comparatively hard bark and Wood of the Douglas fir were easily adaptable to this method and in fact were peeled faster and somewhat more thoroughly than the redwood logs which have a fibrous soft bark. In each of the above examples the bark had already set, but I have found that my method and apparatus is equally effective on sap peeling wood and that the semitight condition of the bark does not appreciably interfere with the efiiciency of my method.

In general I have utilized the principle that the pressure of a stream increases the velocity of the jet from a nozzle and since the kinetic energy of the jet is proportional to the square of the velocity of the jet, by doubling the jets velocity the kinetic energy is increased four-fold. However by increasing the volume or rate of flow through a nozzle, because energy is directly proportional to a change in mass, a doubling of the volume or rate of flow will merely double the kinetic energy of the jet. Therefore greater kinetic energy can be effected from the jet by increasing its velocity. The disadvantage and offsetting factor of this is the fact that the jet tends to disperse at relatively high velocities. I have found that the jet breaks up very quickly at the low volume-high velocity combination. Therefore in order to utilize the jet effectively I place the nozzle forming the jet as close as possible to the bark. I have found this distance to be of the order of from 1 to 3 inches for both the cutting jet and the peeling jet.

I have found it desirable to sometimes vary the distance longitudinally of the log between spiral cuts through the bark depending upon the tenacity with which the bark is xed to the wood portion of the log. This interval can be varied by changing the angle at which the rollers 28 are positioned to the longitudinal axis of ythe log or by use of a single ball caster in place of rollers and regulating the speed of advance of the supporting arm 24 and the jets through the use of a variable speed windlass or hydraulic piston means. In order that the wood portion of the log not be damaged by the debarking operation I have found it necessary to control the depths of cut made by the cutting jet either by decreasing the pressure supplied to its nozzle or by increasing the speed of rotation of the log.

In general my method and apparatus have the advantage of using very small quantities of water to accomplish the debarking operation which results in both a saving of water, which is a great advantage in many timber areas, as Well as a considerable saving in power. The combined action of the two jets disclosed in my method results in peeling a spiral strip of bark from the log which in turn results in a faster operation as Well as an improved product. In addition because of the small quantities of water used the entire operation is simplified and the capital required for its installation is greatly reduced. Because of the simple operation and the small quantities involved and because the effective length of the jets are very short the method avoids many of the inherent dangers to personnel present in the earlier hydraulic debarking operations.

I claim:

1. Apparatus for debarking logs comprising means for rotating the log about its longitudinal axis, means for producing and directing a hydraulic cutting jet in a direction substantially radially of the log, said cutting jet serving to cut REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number `Name Y Date 2,328,545 Bukowsky Sept. '1, 1943 2,342,533 Edwards Feb. 22, 1944 2,587,473 Holveck et al. Feb. 26, 1952 FOREIGN PATENTS Number Country Date 12,523 lNorway May 25, 1903 35,574 Sweden Oct. 1, 1913 

